Kenny Wong, a police inspector on the traffic unit, makes it his personal mission to stop illegal street racing and arrest speeding drivers. He and his subordinates patrol the streets on their motorcycles, ready to prosecute any speeding, dangerous, intoxicated or unlicensed drivers. Kenny has a cold personality and rarely smiles. Of his colleagues, only Benjamin Yuen of the Accident Investigation Unit understands him well. When a rookie with a bubbly personality (Sisley Choi) arrives, everyone thought that she would not be able to withstand Kenny's strict training. But surprisingly, she develops a father-daughter-like mentorship relationship with him. She even helps him find relief from a nagging secret. The envious Benjamin tries to persuade Sisley to transfer to his team because the performance of his subordinate Natalie Tong is unsatisfactory. Benjamin likes to conduct very thorough investigations,which often makes simple cases more complicated than it needs to be. On the other hand, Natalie does things by the books, an attitude which puts her in a tense standoff against Benjamin. Street racing become rampant again and racers are openly provoking the police. As Kenny leads the team to fight back, he pushes himself towards extremely dangerous territory and the dark cloud that had been troubling him for many years re-emerges...
